Capacitor structures have many applications in integrated circuitry, including applications as memory storage devices in DRAM arrays. The capacitor devices can be fabricated as container devices, and can be formed within openings in an appropriate lattice material.
A common method utilized for forming openings is photolithographic processing. Specifically, a photosensitive material is provided over a layer and subsequently patterned with appropriate radiation (typically ultraviolet light). The patterned photoresist is then utilized as a mask during an etch of the underlying layer. The etch is conducted for an appropriate time to form openings either into the layer or extending entirely through the layer.
Problems with photolithographic processing are encountered as efforts are made to increase the density of devices associated with semiconductor substrates (i.e., as efforts are made to increase the scale of integration). For instance, the wavelength of light utilized to pattern photoresist can impart a limitation on the smallest size devices that can be fabricated with a particular photolithographic process. Efforts have been made to overcome such problem by extending photolithographic technologies to utilize smaller-wavelength light. For instance, the wavelength of light typically utilized for photolithographic processing has decreased from 365 nanometers to 248 nanometers, and then decreased from 248 nanometers to 193 nanometers, and now efforts are being made to utilize 157 nanometer wavelength radiation. However, regardless of the wavelength of radiation that is utilized for a particular photolithographic process, the radiation ultimately imposes a limitation on the smallest feature that can be directly patterned into a photosensitive material.
Another problem which can occur during photolithographic processing is that the shapes which can be formed by the processing are limited due to interference effects which occur as the dimensions of the patterned features approach the wavelength of radiation utilized to form the features. For instance, openings are typically elliptical or circular in shape, even though the actual opening formed in a reticle utilized during the photolithographic processing is typically rectangular, square, or otherwise polygonal.
The limitations on feature sizes and shapes that can achieved with photolithographic processing impart limitations on capacitor structure design. It is desired to overcome such limitations.